Pulmonary nocardiosis in a patient with idiopathic CD4 T-lymphocytopenia

Idiopathic CD4 T-lymphocytopenia (ICL) is a rare immunodeficiency characterized by low CD4 T-lymphocyte count, which usually manifests with opportunistic infections. Nocardia as an opportunistic pathogen infecting patients with this condition has rarely been reported. Here, we describe the case of a 46-year-old male who presented with lung mass and respiratory and systemic symptoms and was eventually diagnosed with pulmonary nocardiosis. A workup for predisposing immunodeficiencies suggested a picture of ICL. This case illustrates the importance of considering ICL as a possible predisposing condition when an otherwise healthy individual presents with pulmonary nocardiosis.